<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>动态粒子效果</title>
  <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.js"></script>
  <style>
    html,body {
      width: 100%;
      height: 100%;
      margin: 0;
      padding: 0;
      overflow: hidden;
    }
    .container{
      width: 100%;
      height: 100%;
      margin: 0;
      padding: 0;
      background-color: #000000;
    }
  </style>
</head>
<body>

<div id="jsi-particle-container" class="container"></div>
<script>
  var RENDERER = {
    PARTICLE_COUNT : 1000,
    PARTICLE_RADIUS : 1,
    MAX_ROTATION_ANGLE : Math.PI / 60,
    TRANSLATION_COUNT : 500,
    init : function(strategy){
      this.setParameters(strategy);
      this.createParticles();
      this.setupFigure();
      this.reconstructMethod();
      this.bindEvent();
      this.drawFigure();
    },
    setParameters : function(strategy){
      this.$window = $(window);
      this.$container = $('#jsi-particle-container');
      this.width = this.$container.width();
      this.height = this.$container.height();
      this.$canvas = $('<canvas />').attr({width : this.width, height : this.height}).appendTo(this.$container);
      this.context = this.$canvas.get(0).getContext('2d');
      this.center = {x : this.width / 2, y : this.height / 2};
      this.rotationX = this.MAX_ROTATION_ANGLE;
      this.rotationY = this.MAX_ROTATION_ANGLE;
      this.strategyIndex = 0;
      this.translationCount = 0;
      this.theta = 0;
      this.strategies = strategy.getStrategies();
      this.particles = [];
    },
    createParticles : function(){
      for(let i = 0; i < this.PARTICLE_COUNT; i ++){
        this.particles.push(new PARTICLE(this.center));
      }
    },
    reconstructMethod : function(){
      this.setupFigure = this.setupFigure.bind(this);
      this.drawFigure = this.drawFigure.bind(this);
      this.changeAngle = this.changeAngle.bind(this);
    },
    bindEvent : function(){
      this.$container.on('click', this.setupFigure);
      this.$container.on('mousemove', this.changeAngle);
    },
    changeAngle : function(event){
      var offset = this.$container.offset(),
              x = event.clientX - offset.left + this.$window.scrollLeft(),
              y = event.clientY - offset.top + this.$window.scrollTop();
      this.rotationX = (this.center.y - y) / this.center.y * this.MAX_ROTATION_ANGLE;
      this.rotationY = (this.center.x - x) / this.center.x * this.MAX_ROTATION_ANGLE;
    },
    setupFigure : function(){
      for(var i = 0, length = this.particles.length; i < length; i++){
        this.particles[i].setAxis(this.strategies[this.strategyIndex]());
      }
      if(++this.strategyIndex == this.strategies.length){
        this.strategyIndex = 0;
      }
      this.translationCount = 0;
    },
    drawFigure : function(){
      requestAnimationFrame(this.drawFigure);
      this.context.fillStyle = 'rgba(0, 0, 0, 0.2)';
      this.context.fillRect(0, 0, this.width, this.height);
      for(var i = 0, length = this.particles.length; i < length; i++){
        var axis = this.particles[i].getAxis2D(this.theta);
        this.context.beginPath();
        this.context.fillStyle = axis.color;
        this.context.arc(axis.x, axis.y, this.PARTICLE_RADIUS, 0, Math.PI * 2, false);
        this.context.fill();
      }
      this.theta++;
      this.theta %= 360;
      for(var i = 0, length = this.particles.length; i < length; i++){
        this.particles[i].rotateX(this.rotationX);
        this.particles[i].rotateY(this.rotationY);
      }
      this.translationCount++;
      this.translationCount %= this.TRANSLATION_COUNT;
      if(this.translationCount == 0){
        this.setupFigure();
      }
    }
  };
  var STRATEGY = {
    SCATTER_RADIUS :150,
    CONE_ASPECT_RATIO : 1.5,
    RING_COUNT : 5,
    getStrategies : function(){
      var strategies = [];
      for(var i in this){
        if(this[i] == arguments.callee || typeof this[i] != 'function'){
          continue;
        }
        strategies.push(this[i].bind(this));
      }
      return strategies;
    },
    createSphere : function(){
      var cosTheta = Math.random() * 2 - 1,
              sinTheta = Math.sqrt(1 - cosTheta * cosTheta),
              phi = Math.random() * 2 * Math.PI;
      return {
        x : this.SCATTER_RADIUS * sinTheta * Math.cos(phi),
        y : this.SCATTER_RADIUS * sinTheta * Math.sin(phi),
        z : this.SCATTER_RADIUS * cosTheta,
        hue : Math.round(phi / Math.PI * 30)
      };
    },
    createTorus : function(){
      var theta = Math.random() * Math.PI * 2,
              x = this.SCATTER_RADIUS + this.SCATTER_RADIUS / 6 * Math.cos(theta),
              y = this.SCATTER_RADIUS / 6 * Math.sin(theta),
              phi = Math.random() * Math.PI * 2;
      return {
        x : x * Math.cos(phi),
        y : y,
        z : x * Math.sin(phi),
        hue : Math.round(phi / Math.PI * 30)
      };
    },
    createCone : function(){
      var status = Math.random() > 1 / 3,
              x,
              y,
              phi = Math.random() * Math.PI * 2,
              rate = Math.tan(30 / 180 * Math.PI) / this.CONE_ASPECT_RATIO;
      if(status){
        y = this.SCATTER_RADIUS * (1 - Math.random() * 2);
        x = (this.SCATTER_RADIUS - y) * rate;
      }else{
        y = -this.SCATTER_RADIUS;
        x = this.SCATTER_RADIUS * 2 * rate * Math.random();
      }
      return {
        x : x * Math.cos(phi),
        y : y,
        z : x * Math.sin(phi),
        hue : Math.round(phi / Math.PI * 30)
      };
    },
    createVase : function(){
      var theta = Math.random() * Math.PI,
              x = Math.abs(this.SCATTER_RADIUS * Math.cos(theta) / 2) + this.SCATTER_RADIUS / 8,
              y = this.SCATTER_RADIUS * Math.cos(theta) * 1.2,
              phi = Math.random() * Math.PI * 2;

      return {
        x : x * Math.cos(phi),
        y : y,
        z : x * Math.sin(phi),
        hue : Math.round(phi / Math.PI * 30)
      };
    }
  };
  var PARTICLE = function(center){
    this.center = center;
    this.init();
  };
  PARTICLE.prototype = {
    SPRING : 0.01,
    FRICTION : 0.9,
    FOCUS_POSITION : 300,
    COLOR : 'hsl(%hue, 100%, 70%)',
    init : function(){
      this.x = 0;
      this.y = 0;
      this.z = 0;
      this.vx = 0;
      this.vy = 0;
      this.vz = 0;
      this.color;
    },
    setAxis : function(axis){
      this.translating = true;
      this.nextX = axis.x;
      this.nextY = axis.y;
      this.nextZ = axis.z;
      this.hue = axis.hue;
    },
    rotateX : function(angle){
      var sin = Math.sin(angle),
              cos = Math.cos(angle),
              nextY = this.nextY * cos - this.nextZ * sin,
              nextZ = this.nextZ * cos + this.nextY * sin,
              y = this.y * cos - this.z * sin,
              z = this.z * cos + this.y * sin;

      this.nextY = nextY;
      this.nextZ = nextZ;
      this.y = y;
      this.z = z;
    },
    rotateY : function(angle){
      var sin = Math.sin(angle),
              cos = Math.cos(angle),
              nextX = this.nextX * cos - this.nextZ * sin,
              nextZ = this.nextZ * cos + this.nextX * sin,
              x = this.x * cos - this.z * sin,
              z = this.z * cos + this.x * sin;

      this.nextX = nextX;
      this.nextZ = nextZ;
      this.x = x;
      this.z = z;
    },
    rotateZ : function(angle){
      var sin = Math.sin(angle),
              cos = Math.cos(angle),
              nextX = this.nextX * cos - this.nextY * sin,
              nextY = this.nextY * cos + this.nextX * sin,
              x = this.x * cos - this.y * sin,
              y = this.y * cos + this.x * sin;

      this.nextX = nextX;
      this.nextY = nextY;
      this.x = x;
      this.y = y;
    },
    getAxis3D : function(){
      this.vx += (this.nextX - this.x) * this.SPRING;
      this.vy += (this.nextY - this.y) * this.SPRING;
      this.vz += (this.nextZ - this.z) * this.SPRING;

      this.vx *= this.FRICTION;
      this.vy *= this.FRICTION;
      this.vz *= this.FRICTION;

      this.x += this.vx;
      this.y += this.vy;
      this.z += this.vz;

      return {x : this.x, y : this.y, z : this.z};
    },
    getAxis2D : function(theta){
      var axis = this.getAxis3D(),
              scale = this.FOCUS_POSITION / (this.FOCUS_POSITION + axis.z);
      return {x : this.center.x + axis.x * scale, y : this.center.y - axis.y * scale, color : this.COLOR.replace('%hue', this.hue + theta)};
    }
  };
  $(function(){
    RENDERER.init(STRATEGY);
  });
</script>
</body>
</html>
